1. Field of the Invention
The present invention relates to a method and an apparatus for examining luggage by X-ray scanning, wherein the pieces of luggage to be examined are moved on a conveyor belt into a scanner which contains the X-ray components, i.e., an X-ray unit and a detector unit.
2. Description of the Related Art
Apparatus of the above-described type are known in various configurations. They are used for automatically examining luggage, particularly at airports. For this purpose, the apparatus are integrated into the luggage conveying and handling system of the respective airport. This results in basic requirements concerning dimensions and examination speeds.
In the X-ray scanning method used in connection with the present invention, the X-rays which emanate from an X-ray tube are scattered by the contents of the piece of luggage being examined. This scattered signal is received by a detector and is processed by a subsequently connected electronic unit. The measured spectrum is an indication for the substance contained in the piece of luggage. The measured signal is compared to signals stored in a data bank. If there is a match, an alarm will be given.
There are basically various methods for completely scanning the piece of luggage. In practice, a strip having a width of approximately 5 cm can be scanned in each scanning process. Consequently, when a piece of luggage is large, a plurality of individually scanned strips are used for generating the total picture. This requires a corresponding amount of time.
The piece of luggage is being moved on a conveyor belt. When the X-ray/detector unit is stationary, the piece of luggage must be moved relative to the scanner, for example, in a meander-shaped configuration, between the X-ray tube and the detector in order to carry out scanning with the necessary strip units. For this purpose, the actual conveying unit and the movement of the piece of luggage must be interrupted and changed. This is not acceptable in the case of luggage at airports because each individual piece of luggage would have to be moved, not only in the conveying direction, but also back and forth.